Etymologies

incautious +‎ -ness (Wiktionary)

Examples

With characteristic Anglo-Saxon incautiousness he had brought on board with the rest of his baggage, a case containing no less than thirty pounds of picrate, and had allowed the explosive matter to be stowed in the hold with as little compunction as a Frenchman would feel in smuggling a single bottle of wine.

With characteristic Anglo-Saxon incautiousness he had brought on board, with the rest of his baggage, a case containing no less than thirty pounds of picrate, and had allowed the explosive matter to be stowed in the hold with as little compunction as a Frenchman would feel in smuggling a single bottle of wine.

But now, abruptly and without her having thought of it, he had, with the incautiousness of a soldier who discloses his attack and lays himself open to a bully who tries to provoke him, the duke showed her the extent of his violent passion by a single phrase that feverishly agitated her.